/Engine/Source/Runtime/Engine/Public/ReferenceSkeleton.h
Returns # of Depth from BoneIndex to ParentBoneIndex This will return 0 if BoneIndex == ParentBoneIndex; This will return -1 if BoneIndex isn't child of ParentBoneIndex
int32 GetDepthBetweenBones ( const int32 BoneIndex, const int32 ParentBoneIndex ) const